Abstract

2750

Background: Aberrant DNA methylation patterns, which display global hypomethylation and local promoter hypermethylation in tumor suppressor and growth regulatory genes, are a feature of most cancers, including breast malignancy. Epigenetic fluctuations in the degree of CpG islands represent an important mechanism by which gene function is selectively activated or silenced, as a result of modifying the binding of transcription factors and methyl-DNA binding proteins. A wide range of dietary compounds, such as resveratrol, can lead to global alterations in DNA methylation. Since dietary compounds are likely to induce epigenetic rather than mutational events, assessing changes in methylation, represent excellent targets to elucidate how diet factors may modify cancer risk and tumor behavior. Resveratrol, a compound commonly found in red wine and in the Japanese knotweed plant, possesses recognized health benefits for a wide range of human diseases including cancer. Resveratrol acts as an estrogen receptor (ER) antagonist in the presence of estrogen, leading to growth inhibition of ER positive breast cancer in a dose-dependant fashion. In the absence of estradiol, resveratrol has both agonist and antagonist effects depending on the dose used. Our goal was to determine the dose-dependant methylation effects of resveratrol on ER+ breast cancer cells. Methods: MCF-7 cells were treated with 5μM, 50 μM and 100 μM of resveratrol for 36 hours, DNA and RNA were extracted and differential methylation hybridization assays were conducted to screen an array containing 8716 CpG island tags for changes in methylation. Real-time PCR was also performed to assess expression levels of DNMT1 and DNMT3b, two of the three major isoforms of identified DNA methyltransferases, based on resveratrol treatment. Results and Conclusion: 65 loci have a two-fold or greater change in methylation status. Nine of the loci are genes with known identities, one of which is the tumor suppressor gene DLC-1 which is hypermethylated in various cancers. DLC-1 was demethylated following resveratrol treatment. DNMT1 and DNMT3b levels were inhibited by resveratrol in a dose dependant fashion. Resveratrol induces methylation changes in a variety of CpG islands, including those known to be altered in human cancer. This suggests that alterations in methylation may be an important mechanism by which resveratrol provides protective effects in human disease, including ER+ breast cancer.